142 THE ROYAL SOCIETY OF CANADA 



the munitions plant at Trenton, Ont. This nitre cake is stated "to 

 contain 30 per cent free sulphuric acid, nitric acid not over • 2 per cent 

 and small amounts of iron. Otherwise it is practically free from 

 impurities." The supplies of nitre cake (Trenton), "Florida Pebble 

 Rock and Canadian Apatite used in this experimental work were 

 furnished by the Director of Explosives. 



In the preparation of the materials the nitre cake was reduced 

 in an iron mortar until sufficiently fine to pass through a 60 mesh 

 sieve. No particular difficulty was experienced in this operation. 

 Reduction of the cake in a pebble or ball mill was tried, but this was 

 found to be unsatisfactory, owing to the material adhering to the 

 pebbles. Both the Florida Pebble Phosphate and the Canadian 

 Apatite readily reduced in the pebble mill, screen tests showing that 

 for the former 98 per cent passed the 80 mesh and 78 per cent a 100 

 mesh sieve and for the latter ground product 100 per cent passed 

 the 100 mesh sieve. 



After certain preliminary experiments it was decided to ascertain 

 the action of the nitre cake on the phosphates when (1) the materials 

 were mixed "dry" and (2) when the materials were made into a paste 

 with the addition of a little water. 



In the "dry mix" the powdered substances were weighed out 

 in the several proportions stated in the tables of analysis, thoroughly 

 mixed and placed in glass stoppered bottles. The product or "mix," 

 after being allowed to remain at room temperatures, was analysed 

 at the end of one week.^ The product was a fine, flour-like material, 

 with no evidence of caking. 



In the "wet mix," to the materials mixed in the proportions 

 noted, a small but known weight of water was added and the whole 

 stirred to a damp mass. This was placed in stoppered bottles and 

 allowed to stand 48 hours. The mass was then emptied out and 

 allowed to air-dry. Although a slight caking or hardening took place, 

 it was very readily broken down to a fine powder. The setting or 

 hardening was more pronounced with the Canadian Apatite than 

 with the Florida phosphate, but in both cases a first class product, 

 as regards its mechanical condition, was obtained. 



An outline of the analytical procedure may be given as follows: 

 2 grams of the mix were weighed into a beaker and 200 cc of water 

 added. After occasional stirring for 2 hours the whole was filtered 

 and the filtrate made up to 500 cc and an aliquot taken for the deter- 

 mination of water soluble phosphoric acid. The filter with its residue 

 was then placed in a bottle with 500 cc of a 1 per cent solution of 



'Analyses of "dry" mixes that had been allowed to stand two weeks gave results 

 practically identical with those of one week's standing. 



